Estimates of one to two thousand practitioners circulate in reference works without a dated source behind them, and should be treated as an order of magnitude rather than a count. Dianic Wicca is small.
Its influence, again, is larger than its size. The idea that Goddess religion could be a vehicle for feminist politics rather than a private devotion moved from Dianic circles into the wider pagan world and out of it again. The language of women's mysteries, the reclaiming of the word witch as a badge rather than an accusation, and the treatment of ritual as a form of political action all came through this tradition or alongside it. Reclaiming, which is a substantially different thing, drew on it directly.
Structurally it is loose. There is no central body, no lineage requirement of the Gardnerian kind and no single authority; leadership rests with ordained priestesses and with collectives, and covens are autonomous. Ruth Barrett and others carried the teaching forward and developed it well beyond Budapest's original material.
The tradition's difficulty is generational. Its founding conviction, that women need separate space, was formed in the 1970s among women for whom separatism was a hard-won achievement, and it now meets a younger constituency for whom the category of woman is itself the contested question. Some Dianic groups have resolved this by opening; others have not; and the argument has cost the tradition members on both sides of it, which is the usual price of a question a movement cannot settle.